Power management system switched capacitor voltage regulator with integrated passive device

ABSTRACT

Power management systems are described. In an embodiment, a power management system includes a voltage source, a circuit load located within a chip, and a switched capacitor voltage regulator (SCVR) coupled to voltage source and the circuit load to receive an input voltage from the voltage source and supply an output voltage to the circuit load. The SCVR may include circuitry located within the chip and a discrete integrated passive device (IPD) connected to the chip.

RELATED APPLICATION

This application is a continuation of co-pending U.S. patent applicationSer. No. 16/231,904, filed Dec. 24, 2018, which is incorporated hereinby reference.

BACKGROUND Field

Embodiments described herein relate to power management systems, andmore particularly to switched capacitor voltage regulators.

Background Information

Electronic devices include various integrated circuits for performingdifferent tasks. Often multiple integrated circuits (ICs) are integratedinto a single system on chip (SOC). These ICs may additionally operateat different power supply voltage levels. Power supplies and voltageregulator circuits may be used to supply the various voltage levels foruse by the ICs. For example, switched capacitor voltage regulators(SCVRs) may be implemented to provide independent voltage supplies tovarious circuit loads such as central processing units, graphicsprocessing units, caches, signal I/O's, memory, etc. all on the samechip or separate chips within a system.

SUMMARY

Power management systems with switched capacitor voltage regulators(SCVRs) are described. In particular, the capacitors may be packagedseparately from the circuitry of the SCVRs as discrete integratedpassive devices. In an embodiment, a power management system includes avoltage source, a circuit load located within a chip, and an SCVRcoupled to the voltage source and the circuit load to receive an inputvoltage from the voltage source and supply an output voltage to thecircuit load. The SCVR can include circuitry located within the chip,and a discrete integrated passive device (IPD) connected to the chip.

The power management systems and SCVRs in accordance with embodimentsmay be organized a variety of configurations (e.g. low powerconfigurations, high power configurations), each of which mayadditionally be designed to be operated in a number of nominal, highperformance, and low performance conditions and may support multiplecircuit loads.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a power management system in accordancewith an embodiment.

FIG. 2 is a circuit diagram of an exemplary 2:1 switched capacitorconverter section of the power management system in accordance with anembodiment.

FIG. 3 is a combination schematic cross-sectional side view illustrationand circuit diagram of a power management system in accordance with anembodiment.

FIG. 4 is a schematic cross-sectional side view illustration of trenchcapacitors in accordance with an embodiment.

FIG. 5 is a schematic cross-sectional side view illustration of anintegrated fan-out package configuration of an IPD in accordance withembodiments.

FIG. 6 is a schematic cross-sectional side view illustration of a 2.5Dpackaging integration the IPD in accordance with embodiments.

FIG. 7 is a schematic cross-sectional side view illustration of a CoWpackaging integration in accordance with embodiments.

FIGS. 8-9 are combination schematic cross-sectional side viewillustrations and circuit diagrams of CoW packaging integrations inaccordance with embodiments.

FIG. 10 is a schematic system level diagram of a low power applicationintegration scheme in accordance with an embodiment.

FIG. 11A is a schematic cross-sectional side view illustration andcircuit diagram of a low power integration scheme with integratedfan-out packaging in accordance with an embodiment.

FIG. 11B is a combination schematic cross-sectional side viewillustration and circuit diagram of a low power integration scheme inaccordance with an embodiment.

FIG. 12A is a block diagram illustrating a specific implementation of alow power integration scheme of a power management system in accordancewith an embodiment.

FIG. 12B is a chart illustration droop assist of the during operation ofthe low power integration scheme of FIG. 12A in a high performance modein accordance with an embodiment.

FIG. 13 is a schematic system level diagram of a high power applicationintegration scheme in accordance with an embodiment.

FIG. 14 is a schematic cross-sectional side view illustration andcircuit diagram of a high power integration scheme with 2.5D packagingin accordance with an embodiment.

FIG. 15 is a circuit diagram of a high power integration scheme inaccordance with an embodiment.

FIG. 16 is a block diagram illustrating an implementation of a highpower integration scheme in accordance with an embodiment.

FIG. 17 is a generalized simulation plot of SCVR output voltageefficiency over output voltage range for different conversion ratios ata single input voltage in accordance with embodiments.

FIG. 18 is a flow chart of a method of fabricating a power managementsystem including a single power supply and single circuit load inaccordance with an embodiment.

FIGS. 19A-19C illustrate overlapping efficiency plots for exemplarypower management systems in accordance with embodiments, each includinga single power supply and single circuit load operated in accordancewith the sequence illustrated in FIG. 18.

FIG. 20A illustrates an SCVR efficiency plot for two circuit loadsconnected to a single voltage input in accordance with an embodiment.

FIG. 20B illustrates an SCVR efficiency plot in which there is arelatively small voltage ratio between the two circuit loads inaccordance with an embodiment.

FIG. 20C illustrates an SCVR efficiency plot in which there is arelatively large voltage ratio between the two circuit loads inaccordance with an embodiment.

FIG. 21 is a flow chart of a method of fabricating a power managementsystem including a single power supply and multiple circuit loads inaccordance with an embodiment.

FIGS. 22A-22B are efficiency plots for an exemplary power managementsystem including a single power supply and multiple circuit loadsoperated in accordance with the sequence illustrated in FIG. 21 inaccordance with embodiments.

FIGS. 23A-23B are efficiency plots for an exemplary power managementsystem including a single power supply and multiple circuit loadsoperated in accordance with the sequence illustrated in FIG. 21

DETAILED DESCRIPTION

Embodiments describe power management systems with switched capacitorvoltage regulators, in which the capacitors are packaged separately fromthe circuitry of the switched capacitor voltage regulators as discreteintegrated passive devices. In various embodiments, description is madewith reference to figures. However, certain embodiments may be practicedwithout one or more of these specific details, or in combination withother known methods and configurations. In the following description,numerous specific details are set forth, such as specificconfigurations, dimensions and processes, etc., in order to provide athorough understanding of the embodiments. In other instances,well-known semiconductor processes and manufacturing techniques have notbeen described in particular detail in order to not unnecessarilyobscure the embodiments. Reference throughout this specification to “oneembodiment” means that a particular feature, structure, configuration,or characteristic described in connection with the embodiment isincluded in at least one embodiment. Thus, the appearances of the phrase“in one embodiment” in various places throughout this specification arenot necessarily referring to the same embodiment. Furthermore, theparticular features, structures, configurations, or characteristics maybe combined in any suitable manner in one or more embodiments. Inaddition, the phrase coupled to or coupled with may mean one elementdirectly connected to another element, or connected in an electricalpath than may have one or more intervening elements. The terms “over”,“to”, “between”, and “on” as used herein may refer to a relativeposition of one layer with respect to other layers. One layer “over”, or“on” another layer or bonded “to” or in “contact” with another layer maybe directly in contact with the other layer or may have one or moreintervening layers. One layer “between” layers may be directly incontact with the layers or may have one or more intervening layers.

In an embodiment, a power management system includes a voltage source(e.g. power supply), a circuit load located within a chip, and aswitched capacitor voltage regulator (SCVR) coupled to the voltagesource and the circuit load to receive an input voltage from the voltagesource and supply an output voltage to the circuit load. The SCVR mayinclude circuity located within the chip, and a discrete integratedpassive device (IPD) connected to the chip.

In one aspect, integration of a discrete component IPD allows the use ofadvanced processing nodes, or different nodes than for chip fabrication.Depending on packaging mechanism employed a high pin density can beachieved while locating the IPD close to the SCVR circuitry. Segregationof IPD increases available area since the capacitors are separate fromthe active SOC. This can lead to a lower power density (since largercapacitor can be realized), and increased efficiency. Additionally,since the IPD capacitors are not required to be formed in the samesubstrate as the active SOC, processing sequences and substrate dopingis not tied to SOC logic processing. Therefore, capacitors can befabricated to achieve a higher capacitance density, low equivalentseries resistance, low series inductance, and low parasitics.Furthermore, the IPDs may be packaged using a variety of techniques suchas integrated fan-out packaging, 2.5D packaging (e.g. siliconinterposer), and chip on wafer (CoW) to scale the number of pinsavailable for to support a multitude of circuit loads, phases andconversion ratio modes. Taken together any of the high capacitordensity, low parasitics, number of available pins, and advancedprocessing technology nodes can be implemented to increase the SCVRefficiency compared to a traditional on-chip switched capacitor voltageregulator.

The power management systems and SCVRs in accordance with embodimentsmay be organized a variety of configurations (e.g. low powerconfigurations, high power configurations), each of which mayadditionally be designed to be operated in a number of nominal, highperformance, and low performance conditions and may support multiplecircuit loads.

In some embodiments, the power management system may be configured forlower power delivery, such as in mobile systems. Such a system mayinclude a circuit board including a main (high performance) power supplyconductor connected to the main voltage source (e.g. main power supply),an auxiliary power supply conductor connected to an auxiliary voltagesource (e.g. auxiliary power supply for lower performance state), and aground conductor. The SCVR circuitry located within the chip can becoupled to the auxiliary power supply conductor and the groundconductor, and a voltage output of the SCVR circuitry located within thechip is electrically connected to the main power supply conductor andthe circuit load. The power for high performance state may be deliveredusing the main power network, and the low performance state using theauxiliary network, both optimized for efficiency.

In an embodiment, a method of operating such a power management systemcan include reading a low performance state (and associated binnedvoltage) for a circuit load, selecting a power supply conductor railthat is coupled to a buck inductor, selecting an auxiliary conversionratio for an SCVR coupled between the auxiliary power supply conductorrail and the circuit load, and adjusting an auxiliary voltage inputvalue to the SCVR from the buck inductor to achieve a specified voltageoutput value from the SCVR to the circuit load. The power managementsystem can also be switched to high performance state. This may includereading a high performance state (and required voltage) for the circuitload, selecting a main power supply conductor rail that is coupled to afirst level voltage regulator, and adjusting an output voltage valuefrom the first level voltage regulator to the circuit load. In somecases, the system may be configured to mitigate voltage droop when inhigh performance modes with large current change transients. This mayinclude detecting a voltage droop in voltage supplied to the circuitload, drawing a compensation charge from the SCVR, and supplying thecompensation charge to the circuit load to compensate the voltage droop.These methods may be a small part in overall operation of the powermanagement system to supply a plurality of circuit loads. For example,reading the low performance state for the circuit load may be a part ofreading a corresponding performance state for a plurality of circuitloads, weighted energy usage of the plurality of circuit loads, andbinned voltage information for the plurality of circuit loads. As aresult, a priority may be assigned to the circuit load based on theweighted energy usage of the plurality of circuit loads.

In some embodiments, the power management system may be configured forhigh power delivery, such as encountered in large systems. Such a systemmay include a circuit board including a main power supply conductorconnected to the main voltage source (e.g. main power supply), anauxiliary power supply conductor connected to an auxiliary voltagesource (e.g. auxiliary power supply), and a ground conductor. The SCVRcircuitry located within the chip can include a low power circuitry anda high power circuitry, where the low power circuitry is coupled to theauxiliary power supply conductor and the ground conductor, and the highpower circuitry is coupled to the main power supply conductor and theground conductor. Voltage outputs of the low power circuitry and thehigh power circuitry can be electrically connected so as to provide asingle voltage output rail to the circuit load to operate in high andlow performance modes.

In an embodiment, a method of operating such a power management systemcan include reading a high performance state (and required voltage) fora circuit load, selecting a power supply conductor rail that is coupledto a first level voltage regulator, selecting a conversion ratio for anSCVR coupled between the power supply conductor rail and the circuitload, and adjusting a voltage input value to the SCVR from the firstlevel voltage regulator to achieve a specified voltage output value fromthe SCVR to the circuit load. The power management system can also beswitched to low performance state. This may include reading a lowperformance state (and required voltage) for the circuit load, selectingan auxiliary power supply conductor rail that is coupled to a buckinductor, selecting a conversion ratio for a second SCVR coupled betweenthe auxiliary power supply conductor rail and the circuit load, andadjusting a second voltage input value to the second SCVR from the buckinductor to achieve a specified voltage output value from the secondSCVR to the circuit load. These methods may be a small part in overalloperation of the power management system to supply a plurality ofcircuit loads. For example, reading the high performance state for thecircuit load can include reading a corresponding performance state for aplurality of circuit loads, weighted energy usage of the plurality ofcircuit loads, and binned voltage information for the plurality ofcircuit loads. As a result, a priority may be assigned to the circuitload based on the weighted energy usage of the plurality of circuitloads.

Referring now to FIG. 1 a block diagram of a power management system 100is provided in accordance with an embodiment. As illustrated, the powermanagement system 100 may include a first level voltage regulator 110 tosupply one or more operating voltages. The first level voltage regulator110 may be a component mounted on a circuit board in some embodiments.The first level voltage regulator 110 is operably connected to a powermanagement unit (PMU) 101, which can be contained entirely within an SOCor spread out across multiple locations. The PMU 101 may include acontrol circuit 150 and a switched capacitor voltage regulator (SCVR)120. The SCVR 120 in accordance with embodiments may include, a discreteintegrated passive device (IPD) 130 including at least the capacitors ofthe SCVR 120. IPD 130 may be a low impedance IPD. In interest ofclarity, in the following description and drawings the SCVR 120circuitry including various routing and switches is commonly illustratedand described separately from the IPD 130 to show that IPD 130 may be adiscrete component of the SCVR 120.

In an embodiment the SCVR 120 is located within the SOC. In accordancewith embodiments, the SCVR 120 receives a voltage from voltage input 107(Vin) and provides an output voltage from voltage output 116 to thecircuit load 140. The output voltage to the circuit load is also termedthe load voltage (Vload). The control circuit 150 may receiveinformation for a specified output voltage value, and determine anecessary input voltage value to be supplied by the first level voltageregulator 110 to voltage input 107. Control circuit 150 may also usefeedback control to SCVR 120, to maintain the voltage output 116 rail atdesired voltage level. This determination may be further predicated onSCVR 120 efficiencies for various input voltages and availableconversion ratios of the SCVR 120. The control circuit 150 may be whollyor partially located within the SOC. For example, a portion of thecontrol circuit 150 may alternatively be located on the circuit board orpackage or some combination in the IPD itself. Still referring to FIG.1, one or more SCVRs 120 are coupled to one or more circuit loads 140contained within the SOC. The circuit loads 140 may also be connectedwith the control circuit 150.

FIG. 2 is a circuit diagram of an exemplary 2:1 switched capacitorconverter section of the power management system 100 in accordance withan embodiment. As shown, the circuit board 200 may include a powersupply conductor 106 and a ground conductor 104 coupled to a powersupply 102. A chip 300 (e.g. SOC) includes a voltage input 107electrically connected to the power supply conductor 106 and a groundconnection 105 electrically connected to the ground conductor 104. Asshown, a SCVR 120 circuitry may be located within the chip 300. The SCVR120 includes a plurality of switches Sw1, Sw2, Sw3, Sw4, that may beused to open or close a high voltage channel and low voltage channelconnected to the IPD 130 in order to control the voltage output 116applied to circuit load 140 (e.g. SOC circuit being supplied). Circuitload 140 may also be connected to ground connection 105.

The IPD 130 can be located on-chip or off-chip in accordance withembodiments. For example the IPD 130 may be a discrete component. FIG. 3is a combination schematic cross-sectional side view illustration andcircuit diagram of a power management system 100 in accordance with anembodiment. The illustrated circuit is substantially similar to that ofFIG. 2, with location of components identified within the chip 300, IPD130 and circuit board 200. As illustrated, the chip 300 (e.g. SOC)includes both the SCVR 120 circuitry and circuit load 140. The IPD 130of the SCVR 120 is a discrete component. In the particular 2.5Dpackaging technique illustrated the IPD 130 is bonded to the chip 300with micro bumps 160 and bonded to the circuit board 200 with ball gridarray (BGA) solder bumps 162, though other packaging solutions arecontemplated in accordance with embodiments. As used herein, 2.5Dpackaging generally includes packaging integration techniques such assilicon interposers, chip-on-wafer-on-silicon (CoWoS) and thosespecifically illustrated. In the particular embodiment illustrated, theIPD 130 includes a flying capacitor 400F coupled between then highvoltage channel and low voltage channel, and a decoupling capacitor 400Dcoupled between the voltage output 116 to the circuit load 140 andground connection 105. It is to be appreciated, the particular switchedcapacitor voltage regulator circuity provided is provided forillustrational purposes only, and that embodiments are compatible withalternate switched capacitor voltage regulator circuitries.

FIG. 4 is a schematic cross-sectional side view illustration of trenchcapacitors 400 in an IPD 130 in accordance with an embodiment. Thecapacitors 400 of IPD 130 may be trench capacitors in accordance withembodiments. The trench capacitors 400 may be fabricated using aspecific targeted process with optimized capacitors, or a DRAMfabrication process, for example. In an embodiment IPD 130 includes aresistive substrate 425 (e.g. silicon substrate, or silicon-on-insulator(SOI) substrate) and buildup structure 410 over the resistive substrate425. Resistive substrate 425 referred to herein may also be aninsulating substrate. A plurality of trench capacitors 400 may be formedwithin the resistive substrate 425, with the buildup structure 410including dielectric and metallization layers for interconnection. TheIPD 130 in accordance with embodiments may have a low resistance path tokeep efficiency high.

For example, resistive substrate 425 may be a bulk silicon substrate orSOI substrate. In the exemplary embodiment illustrated, the resistivesubstrate 425 includes a silicon device layer 420 and oxide layer 450. Agrowth substrate portion (not illustrated) may optionally exist tosupport the oxide layer 450. In the particular embodiment illustrated,the trench capacitors 400 include multiple, electrically separate,electrode layers 430 within a trench 421. The resistive substrate 425,or silicon device layer 420, is not required to have a high dopantconcentration to keep the depletion layer capacitance small, therebyreducing parasitic. A traditional deep trench capacitor may include ahighly doped substrate to lower contact resistance and serves as abottom electrode. It has been observed this can create a parasitic backplate capacitance (Cbp) that bleeds charge and lowers SCVR efficiency.Thus, the trench capacitors 400 in accordance with embodiments may befabricated without doping requirements of SOC active devices, or theneed to use a doped substrate as an electrode. The trench capacitors 400in accordance with embodiments may include electrode layers 430 formedof metal or other high conductivity materials. This lowers theequivalent self resistance (ESR), thereby SCVR improving efficiency.Further, metal interconnection layers like metal routing layers 412 caninterconnect the capacitor cells while keeping the ESR low.

The electrode layers 430 may be separated by dielectric layers 440(which may be high-k materials with a dielectric constant greater thansilicon oxide) to form a plurality of self-capacitors (Ct1′, Ct2′, Ct3′,etc.) in parallel. Larger capacitance lowers the effective AC impedanceof the capacitor, thereby improving SCVR efficiency. This enables tuningthe ratio of desirable self-capacitance (Ct) to parasitic capacitance(e.g. Cbp back plate capacitance).

Still referring to FIG. 4, the build-up structure 410 includes aplurality of dielectric layers 416 metal routing layers 412, and vias414. Top passivation layer 404 and contact pads 402 may be provided forfurther packaging. In an embodiment, the resistive substrate 425, orsilicon device layer 420, is characterized by a resistivity of 100-5,000ohm.cm, or more specifically greater than 1,000 ohm.cm. The oxide layer450, a dielectric, may have a much lower resistivity than the silicondevice layer 420, which can also have the effect of increasing thedepletion layer 460 distance. Thickness between a top surface of contactpad 402 to the back side 451 of resistive substrate 425 can bedetermined based on packaging technique. For example, a chip on wafer(CoW) packaging technique with hybrid bond attach may have a thicknessof 10-20 μm. A 2.5D packaging technique with micro-bump attach may havea thickness of 20-40 μm. An integrated fan-out packaging technique withflip chip attach may have a thickness of 30-80 μm. These examples aremerely illustrative, and embodiments are not limited these thicknesses.Various packaging structures are described in further detail with regardto FIGS. 5-9.

Still referring to FIG. 4, through silicon vias (TSVs) 132 mayoptionally be formed through the resistive substrate 425. The TSVs 132may provide an electrical path to connect to the back side 451 of theresistive substrate 425. The TSVs 132 provide a path to the IPD 130capacitors 400, and optionally other devices within the same silicon orother silicon die. Build-up structure 410 may additionally includeinterconnect routing with the TSVs 132 to contact pads 402 on theopposite side. As will become apparent in the following description,TSVs 132 may be included with all packaging structures, though they arenot required. For example, a 2.5D packaging may include through moldvias in place of TSVs or in addition to TSVs.

Referring now to FIG. 5, a schematic cross-sectional side viewillustration is provided of an integrated fan-out package configurationof an IPD in accordance with embodiments. As shown, package 500 includesa chip 300 mounted on a redistribution layer 320 and encapsulated in amolding compound 310. Chip 300 is illustrated as an SOC, include ageneral processing unit (GPU) 302 core and central processing unit (CPU)304 core. BGA solder balls 162 are provided on the opposite side of RDL320 for mounting onto circuit board 200. In the integrated fan-outpackage configuration illustrated, IPD 130 is also mounted onto theopposite side of the RDL 320 laterally adjacent to the BGA solder balls162. For example, IPD 130 is mounted using micro-bumps 160. In anembodiment, the integrated fan-out package configuration may beimplemented to support a reasonable bump density, low power, and lowpackage height. For example, bump/pin density of micro-bumps 160 may be20-1,000/mm².

FIG. 6 is a schematic cross-sectional side view illustration of a 2.5Dpackaging integration for the IPD in accordance with embodiments. Asillustrated, the package 600 includes a chip 300 mounted on aredistribution layer 320 and encapsulated in a molding compound. Aplurality of IPDs 130 are mounted on the RDL 320 with a plurality ofmicro-bumps 160 and encapsulated within a molding compound 330. TSVs 132may optionally be formed in the IPDs 130, and through mold vias 332 mayoptionally be formed through the molding compound 330 between RDL 320and RDL 340 formed on an opposite side. The RDLs 320, 340 moldingcompound 330, and through mold vias 332 may form an interposer layer610. In some embodiments, molding compound 330 can be replaced withvarious interposer wiring and insulator layers. A plurality of BGAsolder balls 162 may be formed on RDL 340 for mounting onto circuitboard 200. In an embodiment, the 2.5D packaging configuration may beimplemented to support a reasonable bump density and higher power, withhigher package height. For example, bump/pin density of micro-bumps 160may be 100-1,000/mm².

FIGS. 7-9 are schematic cross-sectional side view illustrations ofvarious chip on wafer (CoW) packaging integration for the IPD inaccordance with embodiments. The CoW packaging implementation of FIGS.7-9 may be implemented to support a high bump density, higher power,with low package height. For example, bump/pin density of micro-bumps160 may be 10,000-100,000/mm² due to hybrid bonding. Hybrid bonding withCoW integration may also reduce parasitics. Overall, CoW integration mayenable more phases (lower ripple) and more SCVR conversion ratio modesto enable efficiency. As illustrated in FIG. 7, package 700 includesSCVR 120 circuitry located within the chip 300, and the IPD 130 ishybrid bonded to the chip 300 with metal-metal bonds 180 and oxide-oxidebonds 181. In such an embodiment, the chip 300 including both thecircuit load 140 and SCVR 120 creates a second tier thickness inaddition to the IPD 130 thickness. In such a CoW configuration with theSCVR 120 in chip 300, rather than having a voltage regulator and powergate as separate function, the power gate may also act as a voltageregulator switch, thereby saving some area. The last switch (e.g. Sw4)may act as the power gate to circuit to save area. Cost savings may alsobe realized with keeping the IPD 130 passive.

FIG. 8 illustrates a CoW integration package 800 in which the SCVR 120to the IPD 130 is provided as a separate chip 400 which is hybrid bondedto the IPD 130 with metal-metal bonds 180 and oxide-oxide bonds 181. Inthis implementation package thickness includes chip 400 as first tier,and chip 300 as second tier, which can also be hybrid bonded to the IPD130 with metal-metal bonds 180 and oxide-oxide bonds 181. In such aconfiguration, the chip 400 including the SCVR 120 circuitry is firstattached to the IPD 130, and then that assembly is attached to the chip300. FIG. 9 illustrates a CoW integration scheme similar to FIG. 8, witha difference being that the hybrid bonded IPD 130 and chip 400 areattached to chip 300 with micro-bumps 160 in the package 900.

In the following discussion, exemplary low power and high powerintegration schemes are described and illustrated. It is to beappreciated that these configurations and methods are merely exemplary,and strict partitioning into low power and high power is not necessary.Furthermore, while structural configurations may be tailored to low andhigh power/performance operation, the devices and circuit loads mayoptionally still be operated in both low performance mode and highperformance mode. Accordingly, a lower power configuration is notlimited to lower performance mode of operation, and a high powerconfiguration is not limited to high performance mode of operation.Also, some SCVR implementations may not need a decoupling capacitor, orchoose to allocate all IPD capacitors to the “flying” capacitors. Thus,the following implementations are to be understood as exemplaryimplementations of the embodiments.

Referring now to FIGS. 10-11B exemplary low power integration schemes ofa power management system are provided in accordance with embodiments.Some features of this type of system can be any of the following: verystrict height requirements, low cost package, energy conservation duringextensive periods in low performance mode requiring high efficiency,energy source may usually be a battery, and component size needs to betraded off with battery volume (directly impacts energy available).Generally, these can be low power systems found in mobile applications,for example. FIG. 10 is a schematic system level diagram. FIG. 11A is aschematic cross-sectional side view illustration and circuit diagram ofa low power integration scheme with integrated fan-out packaging. It isto be appreciated that integrated fan-out packaging may be oneimplementation for a low power integration scheme with very tight heightrequirements (e.g. mobile, phones, tablets), and embodiments are not solimited. FIG. 11B is a combination schematic cross-sectional side viewillustration and circuit diagram in accordance with an embodiment withtight height requirements (e.g. mobile, phones, tablets). This optioncan also support higher power applications because of high pin densityand closer integration. Notably, FIG. 11B illustrates a 2.5D packagingintegration of the lower power integration scheme including outline 131of IPD 130 encapsulated in a molding compound 330. FIGS. 10-11B show animplementation of a low power integration scheme. External regulator201, has an input source, and produces several output rails, supportingmultiple performance modes of the chip 300 SOC. External regulator 201may include both first level voltage (buck) regulator 110 and highefficiency buck regulator 112 in one or more silicon chips, for example.High efficiency inductor 111 and high efficiency buck inductor 114 maybe external passive components, for example, mounted on the circuitboard 200. Using first level voltage regulator 110, and high efficiencyinductor 111, main power supply is generated and connected to main powersupply conductor 108 rail (for high performance). High efficiencyinductor 111 may be a set of inductors supporting many phases. Usinghigh efficiency buck regulator 112 and high efficiency buck inductor114, auxiliary power supply is generated and connected to conductor 106rail. SCVR 120, using auxiliary power supply conductor 106 rail asinput, produces an output that is tied to voltage output 116 rail.Voltage output 116 rail supplies the circuit load 140. In addition,there may be power gates within circuit load 140, as shown in FIG. 10.While the SOC is in high performance mode (high power), main powersupply conductor 108 rail provides the main power. High efficiency buckregulator 112 may be turned off in case it is not used by any othercircuit. As an option, high efficiency buck regulator 112 may provide a“boost” option to reduce droop, and discussed later (FIG. 12). Whilechip 300 SOC is in lower performance state (lower power) mode, the(main) first level voltage regulator 110 may be turned off, ifsupporting no other circuits. The more efficient combination of highefficiency buck regulator 112, high efficiency buck inductor 114, andSCVR 120 is used to supply the circuit load 140.

In an embodiment, when the circuit load 140 is in high performance moderequiring high wattage and high voltage, the first level voltageregulator 110 supplies the power to the main power supply conductor 108.When the circuit load 140 is in low performance mode, requiring lowerwattage and low voltage, then the high efficiency buck regulator 112(e.g. from the auxiliary voltage source) is used to supply power to theauxiliary power supply conductor 106. The SCVR 120 converts the voltageon auxiliary power supply conductor 106 to the appropriate levelrequired by the circuit load 140. Further in the lower performance mode,the first level voltage regulator 110 output can be tristated, or it maybe turned off so that the main power supply conductor 108 isdisconnected with the circuit load 140.

The SCVR 120 in accordance with embodiments may additionally providetransient droop assist in high performance states. For example, the SCVRcan replace lost charge quickly, while the external first level voltageregulator 110 responds. This may reduce the AC/transient droop, therebyimproving efficiency.

Referring now to FIGS. 12A-12B, FIG. 12A is a block diagram illustratinga specific implementation of a low power integration scheme of a powermanagement system similar to FIG. 10 operating in a high performancestate, or boost case, in accordance with an embodiment, and FIG. 12B isa chart illustration droop assist of the during operation of the lowpower integration scheme of FIG. 12A in accordance with an embodiment.Main power supply 110VR may include either or both the first levelvoltage regulator 110 (e.g. silicon portion) and high efficiencyinductor 111 (e.g. passive component). Auxiliary power supply 112VR mayinclude either or both the high efficiency buck regulator 112 (e.g.silicon portion) and high efficiency buck inductor 114 (e.g. passivecomponent). Specifically, when the low power integration scheme isoperating in the high performance state (e.g. higher peak current) theSCVR 120 can act as an assist to replace lost charge quickly while thefirst level voltage regulator 110 responds. If there is no assist, thevoltage will droop as shown in FIG. 12B. With boost in accordance withthe embodiment, the voltage may droop as shown in the dashed line. Theextra dip is avoided. With no assist, the dip may be compensated byraising the nominal voltage, so the minimum voltage point is above acertain required minimum point. With the assist, the nominal voltage canbe reduced by the extra dip amount. Power is V*V (V squared) term, so ithelps with power reduction.

It may be possible to provide droop assist as follows. When circuit load140 is operating in a high performance, high voltage mode, turn on (orother low to high current draw events) transients may cause a droop involtage output 116 rail, as shown in FIG. 12B. The SCVR can help replacethis transient charge deficiency, until the first level voltageregulator 110 and power distribution network respond. Assuming thecircuit load 140 needs high power voltage (Vhp) in the high performancemode, and is supplied by the main power supply conductor 108 rail,during such high performance load, the auxiliary power supply conductor106 rail can be set at a higher voltage (n*Vhp), and the SCVR set in an:1 mode (e.g. for n=2, power supply conductor 106 rail is at 2 Vhp, andSCVR at 2:1 mode). If the PMU detects a droop requiring assists, the PMUcontrol triggers SCVR 120, and then it can draw charge from the powersupply conductor 106 rail (now set at a higher voltage), in particularthe local decoupling capacitor 401, and supply the on-chip voltageoutput 116 (Vload) rail connected to the circuit load 140.

In an embodiment, a method of operating a power management system withdroop assist includes reading a performance state and an associatedbinned voltage for a circuit load 140, selecting a main power supplyconductor 108 rail for the circuit load, detecting a voltage droop onvoltage output 116 rail (voltage supplied to the circuit load), drawinga compensation charge from an SCVR 120 whose input is coupled to anauxiliary power supply conductor rail 106 and output is coupled to thevoltage output 116 rail, and supplying the compensation charge to thecircuit load 140 to compensate the voltage droop. The nominal operatingvoltage for the main power supply conductor 108 rail may be higher thanthat for the auxiliary power supply conductor 108 rail. Accordingly, thedroop assist method may additionally include raising a voltage of theauxiliary power supply conductor rail 106 from an existing nominaloperating voltage (possibly corresponding to another performance state)prior to supplying the compensation charge to the circuit load 140. TheSCVR path (auxiliary power supply conductor rail 106 and SCVR 120)mainly supplies a transient charge in high performance mode.

Referring now to FIGS. 13-15 exemplary high power integration schemes ofa power management system are provided in accordance with embodiments.Some features of this type of system can be any of strict (but morerelaxed than FIG. 10) height requirements, moderate cost package, energyconservation during extensive periods in low performance mode requiringhigh efficiency, energy source may not be a battery but a power supply,and more relaxed component size. Generally, these can be moderate tohigh power systems found in higher performance mobile, desktops orlarger applications. FIG. 13 is a schematic system level diagram. FIG.14 is a schematic cross-sectional side view illustration and circuitdiagram of a high power integration scheme with 2.5D packaging. FIG. 15is a circuit diagram. It is to be appreciated that 2.5D packaging is oneimplementation for a high power integration scheme, and embodiments arenot so limited.

As illustrated in FIGS. 13-15, the power management system 100 mayinclude a circuit board 200, a main power supply 110VR and auxiliarypower supply 112VR for auxiliary (low) voltage supply. Main power supply110VR may include either or both the first level voltage regulator 110and high efficiency inductor 111. Auxiliary power supply 112VR may bebuck based, or use other techniques. For example, auxiliary power supply112VR may include either or both the high efficiency buck regulator 112and high efficiency buck inductor 114. As shown in FIG. 14, the circuitboard 200 may include a main power supply conductor 108 (for high power)and a ground conductor 104, as well as an auxiliary power supplyconductor 106 (for low power). The main power supply conductor 108 inFIG. 14 supplies a high voltage to the series of switches Sw1 etc. inthe SCVR 120H for high power, while the auxiliary power supply conductor106 supplies a low voltage to the series of switches Sw1 etc. in theSCVR 120L for low power. In general, the two combinations of inputvoltage rails combined with corresponding SCVR to generate the requiredload voltage level can be extended to many voltage rails and SCVRcombinations, based on system optimization.

As illustrated, the circuit board 200 may include a main power supply110VR coupled to a main power supply conductor 108 and ground conductor104, and auxiliary power supply 112VR coupled to an auxiliary powersupply conductor 106 and the ground conductor 104. A chip 300 (e.g. SOC)includes a voltage input 107 electrically connected to the main powersupply conductor 106 and a ground connection 105 electrically connectedto the ground conductor 104. Chip 300 additionally includes an auxiliaryvoltage input 107L electrically connected to the auxiliary power supplyconductor 106 and a ground connection 105L electrically connected to theground conductor 104.

SCVR 120H is coupled to the main power supply conductor 108, groundconnection 105 and voltage output (Vload) 116H to provide high power tothe common circuit load 140. SCVR 120L is coupled to the auxiliary powersupply conductor 106, ground connection 105L and voltage output (Vload)116L to provide low power to the common circuit load 140. Asillustrated, voltage outputs 116H, 116L are electrically connected andengaged so as to provide a single voltage output 116 rail to the commoncircuit load 140 to operate in high and low performance modes.

A configuration such as those in FIGS. 13-15 may be applicable to manyload scenarios (e.g. FIG. 23A-23B), or a case may loads want a largerange of voltages (extremely low, to maximum). Here the “small” powerload (PL) may be larger because many circuit blocks may be supplied (seeFIG. 16 for example), thereby making the load larger (PL″>PL). Here thebuck efficiency may not be as low as the extreme small mobile formfactor cases. The buck inductor 114 (associated with the auxiliary powersupply 112VR) size may be larger (lower resistance). In a way, even thehigh power configuration is now using the low power configurationtechnique; increase the voltage at the buck source, reduce the current,reduce the buck loss and board package IR loss, and then convert to adesired voltage at destination using the SCVR.

In an embodiment, when the circuit load 140 is in the high performancemode requiring high wattage and high voltage, the main power supply110VR is used. The SCVR 120H is used to convert the high voltage on mainpower supply conductor 108 rail to the appropriate level for the circuitload 140. The voltage and SCVR mode are coordinated to provide a highefficiency operation point. Similarly, when the circuit load 140 is inlower performance mode, low wattage and low voltage are required. Inthis case the auxiliary power supply 112VR is used. SCVR 120L is used toconvert higher voltage on the auxiliary power supply conductor 106 railto an appropriate load required voltage. The input voltage level andSCVR mode are coordinated to provide a high efficiency operation point.The main power supply 110VR and auxiliary power supply 112VR shown canboth optimize efficiency to their power levels. Also it may be possiblein a general case than many loads are being serviced, each in their ownperformance state, and the main power supply 110VR and auxiliary powersupply 112VR may be required to ensure high performance and lowperformance voltages are available.

In the foregoing discussion, the configurations illustrated included atleast two power supply conductor rails including auxiliary power supplyconductor 106 (for low power), and main power supply conductor 108 (forhigh power). These cover the case where one circuit load can be in highperformance mode (e.g. needing high watts/current, and high voltage) andneeds to have high efficiency voltage regulator. These also cover thecase where one circuit load can be in low performance mode (e.g. needinglow current, usually for extensive time, and high efficiency). The PMUhas the choice of selecting between the rails to get the highestefficiency point.

FIG. 16 is a block diagram illustrating an implementation of a highpower integration scheme of a power management system in accordance withan embodiment. As shown, the chip 300 may include various circuit loadsincluding a general processing unit (GPU) 302 circuit load 140,efficient central processing unit (ECPU) 304E circuit load 140, andperformance central processing unit (PCPU) 304P circuit load 140. Thecircuit board 200 includes a main power supply conductor 108 (for highpower), a ground conductor 104, and an auxiliary power supply conductor106 (for low power). A main power supply 110VR may also be on thecircuit board 200, and coupled with the main power supply conductor 108(for high power) and ground conductor 104 in order to adjust powersupplied to the main power supply conductor 108. An auxiliary powersupply 112VR may be similarly located and coupled with the auxiliarypower supply conductor 106. In the embodiment illustrated, both arespective SCVR 120H for high power and SCVR 120L for low power can becoupled to each circuit load (e.g. 302, 304E, 304P) to supply a main(high power) or auxiliary power (low power). In the exemplaryimplementation illustrated, the auxiliary power supply conductor 106,and SCVR 120L are optionally not connected for some circuit loads (e.g.for GPU 302), with optional connections illustrated by dashed lines.Likewise, depending on circuit requirements, the main power supplyconductor rail and SCVR (120H) may be skipped. Further it should benoted that the SCVR 120L and 120H are sized to provide appropriate powerto individual circuit blocks i.e. they will likely be different.

Still referring to the system illustrated in FIG. 16 the embodimentincludes at least two power supplies (main power supply 110VR andauxiliary power supply 112VR) and corresponding rails, and many moreloads (302, 304E, 304P, etc.) each of which may be on/off independently.The number of operation variables includes each load circuit in eachperformance state (high, low, off). To meet these demands the PMU canselect the appropriate SCVR mode and voltage supply (selection of mainpower supply conductor 108 rail or auxiliary power supply conductor 106Lrail). Selection of voltage supply can be changed for a global optimumat the performance state, and may change over time. Methods of operationillustrated and described below with regard to FIGS. 18 and 21 may beutilized for a global optimization in accordance with embodiments. Thisis graphically illustrated in FIGS. 19A-19C, 20A-20C, 22A-22B, 23A-23B.Specifically, FIGS. 19A-19C illustrated one implementation with a singleexternal voltage regulator, two SCVRs, and two circuit loads. FIGS.22A-23B illustrate one implementation with a single external voltageregulator, two or more SCVRs, and two or more circuit loads. In eitherimplementation, it is understood a second voltage regulator may also bepresent and used for other performance modes (e.g. low or high).

FIG. 17 is a generalized typical plot of SCVR output voltage efficiencyover output voltage range for different conversion ratios at a singleinput voltage in accordance with embodiments. Also shown is a relativecomparison with a buck-style regulator, whose efficiency is relativelystable over the output voltage (shown as baseline). As shown, the SCVRsin accordance with embodiments may operate more efficiently at discretevoltage levels set at ratios between voltage input 107 (Vin) values andvoltage output 116 (Vload) values. Corresponding to these modes, thereis a resulting “saw-tooth” efficiency curve. As described in furtherdetail below, high residency state ranges 1710 can be identified foreach conversion ratio mode of operation above a nominal baseline value.Such high residency state ranges 1710 may be correlated with being in anacceptable operational range for the circuit load, particularly whenaccommodating multiple loads or operating conditions of the circuitload, such as high power operational mode or power saving mode.Operating in regions 1710 can save net energy, while efficiency goingbelow a baseline would result in a poor tradeoff. It is to beappreciated that the specific modes illustrated are exemplary, andactual implementations may vary.

Selection of the SCVR operating conditions can be made at the initialdesign and manufacturing stages of the power management system inaccordance with embodiments.

Referring now to FIG. 18 a flow chart is provided of a method offabricating a power management system including a single power supplyand single circuit load in accordance with an embodiment. Thus, this maybe a single load, single external voltage regulator, single SCVR case.Block 1810 is directed to the initial architecture and design phase forthe system, where performance states (e.g. high power or low power, forexample associate with high frequency or low frequency operation) of thecircuit loads and nominal SCVR 120 voltage output 116 values to thecircuit loads are determined. Block 1820 is directed to the initialmanufacturing and test binning phase for the system in which, for eachperformance state, SCVR 120 data is tested and binned. This may includeactual SCVR 120 voltage output 116 values, and SCVR 120 efficiency graphdata over a range of output voltages (e.g. such as data presented inFIG. 17), and for a range of voltage input 107 values.

The manufacturing sequence continues in blocks 1830-1870. At block 1830a test circuit may be used to read the circuit load performance stateand binned voltage information, which may be stored in a lookup tablewithin control 150, and determine a peak efficiency point for each SCVR120 conversion ratio mode. At block 1840, for each circuit loadperformance state, based on the referenced lookup table information, theSCVR 120 conversion ratio mode and first level voltage regulator 110voltage output value, which corresponds to the SCVR 120 voltage input107 (Vin), are selected. At block 1850 the selected first level voltageregulator 110 voltage output value is inspected to determine whether theselected value is within expectations and safe limits. If the values arewithin the prescribed ranges, then the information (performance state,SCVR mode, and first level voltage regulator output voltage) are fusedto control 150 at block 1870. If a violation exists, then at block 1860the next most efficient SCVR mode is selected, and block 1840 isrepeated to select the associated first level voltage regulator 110output voltage value. The final fused values are sufficient, optimizedand compatible with the PMU firmware to set required binned voltage,switched capacitor modes, and external voltage regulator modes for eachrequired state.

Referring now to FIGS. 19A-19C reference is made to efficiency plots fortypical SCVRs in accordance with embodiments to illustrate design andtesting for the manufacturing sequence of power management system with asingle power supply and single circuit load in accordance with thesequence illustrated in FIG. 18. In the embodiment of FIG. 19A, thesingle input voltage (voltage input 107) is constrained to a onceselectable input level for the rail. It is demonstrated that using theSCVR switching modes that one can optimize the efficiency for this chipensemble. In FIG. 19A, an efficiency plot corresponding to operation1820 is provided for multiple chips 300 in a single power supply andsingle circuit load. For example, chip 1 and chip 2 may be the same chipdesign with different binning due to manufacturing, or have beenassembled in different manufacturing and assembly processes. Theefficiency plot of FIG. 19A illustrates that for the same SCVR 120voltage input 107 value, that the actual SCVR 120 voltage output 116values are different, and that chip 1 is operating at a higherefficiency that chip 2 does with the same voltage input 107 value. Thus,this suggest that the required SCVR 120 voltage output 116 values to thechips (i.e. circuit loads) required to operate at a nominal chipfrequency may be different. The nominal chip design voltage may be 1000mV for a performance state (1V is normalized voltage for illustration).After manufacturing one chip, chip 1 may require a binned value ofapproximately 1100 mV, while another chip, chip 2, may require a binnedvalue of 925 mV. FIG. 19B shows the efficiency improvement for chip 1.Here a SCVR operation mode of 3:2 is selected, with an input voltage ofapproximately 1850 mV to obtain the required 1100 mV. For chip 2, a SCVR2:1 mode is selected with the same input voltage of approximately 1850mV to obtain 925 mV. Both resulting voltage points are serviced at ahigher efficiency. Thus, FIGS. 19A-19C illustrate application of thedesign and test fabrication sequence illustrated in FIG. 18 to two typesof systems. For example, the one board voltage source rail (connected tovoltage input 107) may be servicing two different chips on the samecircuit board with each chip requiring different binned voltage levels,or two different chips (each requiring different voltage) on differentcircuit boards, but with board rail (connected to voltage input 107) isa once selectable level for all the boards. It is to be appreciated thatwhile this description shows the case where one can tune the SCVR modeto get better efficiency points this is only one variable. Anothervariable includes changing the input voltage itself. Between the twovariables, overall better efficiency points can be obtained for multipleSCVR/load configurations.

FIGS. 20A-20C illustrate exemplary applications of a power managementsystem in accordance with embodiments. Often a PMU will need to deliverpower to multiple circuit blocks (e.g. CPU/GPU; or core(s) of a CPU, ora high performance CPU (PCPU) and an efficient CPU (ECPU); or GPUcore(s) or other equivalents). Each of these circuit blocks may operateat its own target voltage corresponding to a performance state (e.g.PCPU may be set at 1 V, and ECPU at 0.85 V. The voltage should be readas normalized unit to illustrate the point). Further, there is a netdistribution of “binned” voltage near the voltage design point becauseof actual chip manufacturing process variations. Binned voltage is aprocess of establishing just sufficient minimum voltage to meet thecircuit performance criteria, and in the process minimizing power.Typical variation distribution may be +−5% around the design point (e.g.1.05 to 0.95 for PCPU, and 0.8075 V and 0.89 V for ECPU.). FIG. 20Aillustrates an SCVR efficiency plot for two circuit loads PCPU 304P andECPU 304E connected to a single voltage input 107. Dot size representsenergy usage at a performance state, with a larger dot representing thecircuit load consuming the most energy. Also illustrated is a baselineefficiency level, above which is identified as an acceptable operatingcondition for the system. After binning, in the initial stateillustrated in FIG. 20A, the largest energy consumer PCPU 304P is belowthe baseline efficiency level. The power management system in accordancewith embodiments may allow adjustment of a number of parameters inaccordance with embodiments, such as input voltage, output voltage,conversion ratios, and relative output voltages to the circuit loads(Vload). Adjustment of these parameters may also be dependent uponnumber of circuit loads, comparable energy usage of the circuit loads,and number of power supplies. By way of example, FIG. 20B illustratesone embodiment in which the issue in FIG. 20A may be remedied. In suchan embodiment, the input voltage and conversion ratio mode may beadjusted to increase overall efficiency. As illustrated, the singlevoltage input 107 value is adjusted from a nominal value (V_in_nom) to amodified value (V_in_mod+). Suitably adjusting the input voltage andswitched cap mode, the overall efficiency can be improved. Circuit loadPCPU 304P can be connected to a first SCVR 120, with circuit load ECPU304E is connected to a second SCVR 120, each SCVR 120 operating at adifferent conversion ratio mode. FIG. 20C shows another example. In thisexample, the ratio between PCPU and ECPU has increased, and is alsoinverted due to binning. In this case, the voltage input 107 value isdecreased to a modified value (V_in_mod−) such that the higher energyusage block is at its peak. The curve can be shifted within legal inputvoltage, output voltage, and SCVR modes available.

Generalizing, there may be more loads requiring optimization, than thenumber of options (SCVR modes, external VR number and settings).Therefore, an ensemble optimum efficiency has to be selected. Referringnow to FIG. 21 a flow chart is provided that includes sequences for bothdesign and test, as well as method of operation of a power managementsystem including a single power supply and multiple circuit loads andcorresponding SCVR in accordance with an embodiment. The sequenceillustrated in FIG. 21 can relate to maintaining high efficiency for two(or more) circuit loads on the same chip, such as a CPU and GPU on thesame chip. Thus, this may be a multiple load, single external voltageregulator, multiple SCVR case.

Block 2110 is directed to the initial architecture and design phase forthe system, where performance states (e.g. high power, low power) of thecircuit loads and nominal SCVR 120 voltage output 116 values to thecircuit loads (Vload) are determined. In addition, energy usage for eachcircuit load is weighted, and SCVR efficiency plots are created. Block2120 is directed to a manufacturing and test binning phase for thesystem. It is appreciated that the data collected is specific to thesystem, and each circuit load. Specifically, binned test data mayinclude, for each performance state, actual SCVR 120 output voltages,SCVR 120 efficiency over a range of output voltages (e.g. such as datapresented in FIG. 17), and for a range un input voltages. Thisinformation is then fused, for example to control 150.

The process sequence beginning at block 2130 may then be performedduring actual use of the fabricated power management system 100 inaccordance with embodiments. Thus, the sequence may be utilized for onthe fly power management. At block 2130 control 150 may be used to readthe multiple circuit load performance states, weighted energy use, andbinned voltage information, which may be stored in a lookup table withincontrol 150, and determine the required operating voltage (Vload) foreach circuit load, which also corresponds to the SCVR 120 voltage output116. At block 2140 the control 150 may assign a higher priority to thehigher energy usage circuit load. At block 2150, for the highest energyusage circuit load, the control may first select the SCVR 120 conversionratio mode and first level voltage regulator 110 output voltage value,which corresponds to the SCVR 120 voltage input 107 (Vin) values for thehigher energy usage circuit load. At block 2160, with the first levelvoltage regulator 110 output voltage value already selected, the control150 may select the SCVR 120 conversion ratio mode for the next highestenergy usage circuit load, and so forth for multiple circuit loads. Atblock 2170 a weighted efficiency is calculated. A sweep through blocks2150-2170 is performed to validate maximum weighted efficiency. At block2180 the optimum efficiency point is selected (performance state foreach circuit load, SCVR mode for each circuit load, and first levelvoltage regulator output voltage).

FIGS. 22A-22B are efficiency plots for an exemplary power managementsystem including a single power supply and multiple circuit loadsfabricated and operated in accordance with the sequence illustrated inFIG. 21. In the example provided in FIG. 22A, an efficiency plotcorresponding to operation 2120 is provided for multiple, weightedcircuit loads. For example, circuit 1 and circuit 2 may be differentcircuits (e.g. CPU, GPU) within a single chip 300. If nothing is done,then circuit 2 will operate at a poor efficiency. FIG. 22B relates toselection of the optimum (weighted) efficiency point from operation2180. In this case, circuit 1 is the prioritized circuit of highestenergy usage. As shown, the first level voltage regulator 110 outputvoltage, and corresponding SCVR 120 voltage input 107 (Vin) value, isadjusted while maintaining the SCVR for circuit 1 at a 3:2 conversionratio mode, and changing the SCVR for circuit 2 to a 2:1 conversionratio mode.

FIGS. 23A-23B are efficiency plots for an exemplary power managementsystem including a single power supply and multiple circuit loadsfabricated and operated in accordance with the sequence illustrated inFIG. 21. While only two circuit loads are illustrated, embodiments mayinclude larger multiples of circuit loads. FIGS. 23A-23B are similar toFIGS. 22A-22B, with a difference being that circuit 2 is the prioritizedcircuit of highest energy usage. FIG. 23B relates to selection of theoptimum (weighted) efficiency point from operation 2180. As shown, thefirst level voltage regulator 110 output voltage, and corresponding SCVR120 voltage input 107 (Vin) value, is adjusted while changing the SCVRfor circuit 2 to a 2:1 conversion ratio mode, and maintaining the SCVRfor circuit 1 at a 3:2 conversion ratio mode. In this case, the firstlevel voltage regulator 110 output voltage is adjusted to reach amaximum efficiency value of circuit 2, compared to the previous exampleof FIG. 22B in which the weighted efficiencies resulted in neithercircuit load operating at the maximum efficiency of the correspondingSCVR. This can be generalized to multiple power rails corresponding topower states (high performance state, high wattage, high voltage; versuslow performance state, lower wattage, lower voltage) as shown in FIG.16. For each performance point of each circuit global optimizationpoints are selected, corresponding to external voltage regulatorvoltages, SCVR modes. For example, in the embodiment illustrated in FIG.23B, when circuit 1 and circuit 2 are both in high performance mode,power supply conductor 106 rail is selected for both circuit loads.Thus, power supply conductor 106 voltage is optimized, along with therespective SCVR modes to provide global efficiency optimization. Now ifone of the circuit loads goes into a low performance mode, circuit 2 forexample, while circuit 1 remains in high performance mode, then the PMUmay select the auxiliary power supply conductor 106L and optimize thevoltage and SCVR mode.

In utilizing the various aspects of the embodiments, it would becomeapparent to one skilled in the art that combinations or variations ofthe above embodiments are possible for designing and operating a powermanagement system with a switched capacitor voltage regulator. Althoughthe embodiments have been described in language specific to structuralfeatures and/or methodological acts, it is to be understood that theappended claims are not necessarily limited to the specific features oracts described. The specific features and acts disclosed are instead tobe understood as embodiments of the claims useful for illustration.

What is claimed is:
 1. A power management system comprising: a circuitboard including: a power supply conductor; and a ground conductor; achip coupled to the circuit board, the chip including a switchedcapacitor voltage regulator (SCVR) circuit and a circuit load, the SCVRcircuit including: a voltage input electrically connected to the powersupply conductor; a ground connection electrically connected to theground conductor; a voltage output connected to the circuit load; a highvoltage circuit path running between the voltage input and the voltageoutput; and a low voltage circuit path running between the groundconnection and the voltage output; a discrete integrated passive device(IPD) connected to the chip, the discrete IPD including a flyingcapacitor coupled between the high voltage circuit path and the lowvoltage circuit path.
 2. The power management system of claim 1, furthercomprising a first plurality of switches along the high voltage circuitpath and a second plurality of switches along the low voltage circuitpath.
 3. The power management system of claim 2, wherein the flyingcapacitor is coupled to the high voltage circuit bath between switchesof the first plurality of switches and coupled to the low voltagecircuit path between switches of the second plurality of switches. 4.The power management system of claim 2, wherein the flying capacitor isa trench capacitor.
 5. The power management system of claim 2, whereinthe discrete IPD includes a decoupling capacitor coupled between thehigh voltage circuit path and the ground connection.
 6. The powermanagement system of claim 5, wherein the ground connection is coupledto the circuit load.
 7. The power management system of claim 2, whereinthe discrete IPD includes a first through silicon via (TSV) connectingthe voltage input of the SCVR circuit to the power supply conductor ofthe circuit board.
 8. The power management system of claim 7, whereinthe discrete IPD includes a second through silicon via (TSV) connectingthe ground connection of the SCVR circuit to the ground conductor of thecircuit board.
 9. The power management system of claim 1, wherein: thecircuit board includes an auxiliary power supply conductor; and the SCVRcircuit includes: an auxiliary voltage input electrically connected tothe auxiliary power supply conductor; an auxiliary ground connectionelectrically connected to the ground conductor; an auxiliary voltageoutput connected to the circuit load; an auxiliary high voltage circuitpath running between the auxiliary voltage input and the auxiliaryvoltage output; and an auxiliary low voltage circuit path runningbetween the auxiliary ground connection and the auxiliary voltageoutput; and the discrete IPD includes an auxiliary flying capacitorcoupled between the auxiliary high voltage circuit path and theauxiliary low voltage circuit path.
 10. The power management system ofclaim 9, wherein the voltage output and the auxiliary voltage output areelectrically connected and engaged so to provide a single voltage outputrail to the circuit load to operate in different performance modes. 11.The power management system of claim 1: further comprising a secondcircuit load located within the chip; wherein the SCVR circuit includes:a second voltage input electrically connected to the power supplyconductor; a second ground connection electrically connected to theground conductor; a second voltage output connected to the secondcircuit load; a second high voltage circuit path running between thesecond voltage input and the second voltage output; and a second lowvoltage circuit path running between the second ground connection andthe second voltage output; wherein the discrete IPD includes a secondflying capacitor coupled between the second high voltage circuit pathand the second low voltage circuit path.
 12. The power management systemof claim 1, wherein the voltage source is a voltage regulator mounted onthe circuit board.
 13. The power management system of claim 1, whereinthe discrete IPD includes a plurality of trench capacitors.
 14. Thepower management system of claim 13, wherein the plurality of trenchcapacitors is formed in a resistive substrate.
 15. The power managementsystem of claim 14, wherein the IPD is bonded to the chip with aplurality of micro bumps.
 16. The power management system of claim 15,wherein the IPD is laterally adjacent to a plurality of solder bumpsconnecting the chip to a circuit board.
 17. The power management systemof claim 15, further comprising a plurality of through silicon vias(TSVs) extending through the resistive substrate laterally adjacent tothe plurality of trench capacitors.
 18. The power management system ofclaim 14, wherein the IPD is embedded in an interposer layer between thechip and a circuit board.
 19. The power management system of claim 18,further comprising a plurality of vias extending through the interposerlayer.
 20. The power management system of claim 1, wherein the IPD ishybrid bonded to the chip.